Endothelium-dependent and -independent responses of coronary arteriole to pulsatile mechanical stress in vivo

我们组织这个项目是为了更好地了解脉动机械应力下冠状动脉微动脉内皮依赖性和非独立性调节的生理意义。以下是该项目的主要发现。借助针头-探针式电荷耦合器件活体显微镜和冠状动脉灌注系统，我们评估了冠状动脉小动脉对冠脉灌注压降低的反应。微动脉搏动性跨壁压对冠脉灌流压降低的反应是微动脉扩张的原因。同时，通过降低灌流压力减少冠脉流量时，舒张期时间分数增加。这些与搏动相关的血管扩张和舒张期灌流时间的调节可以为低灌流压下的心肌，特别是心内膜下心肌的供需匹配提供重要的调节机制。

We organized this project in order to provide a better understanding of the physiological importance of the endothelium-dependent and -independent regulations of coronary arteriole under pulsatile mechanical stress. Followings are the major findings this project.With aids of needle-probe CCD intravital microscopy and coronary perfusion system, we evaluated the behavior of the coronary arterioles in response to a reduction of coronary perfusion pressure. Pulsatile transmural pressure of the arterioles contributed to the arteriolar dilation in response to a decrease in coronary perfusion pressure. At the same time, diastolic time fraction increased when coronary flow was reduced by lowering perfusion pressure. These pulsation-related vasodilation and modulation of diastolic perfusion time can provide an important regulatory mechanism to match supply and demand of the myocardium at low perfusion pressure, especially in the subendocardium.